NIAGARA FALLS, N.Y. (AP) — New York state officials say the latest discharge near Niagara Falls is believed to be a rain-related sewer overflow and unrelated to a release last month that turned the water below the world-famous attraction black and smelly.

Department of Environmental Conservation Deputy Commissioner Kenneth Lynch briefed reporters Wednesday, a day after reports of discolored water on the U.S. side of the falls, which straddle the border with Canada.

Lynch says heavy rains likely caused an overflow at a local wastewater treatment plant, but says the DEC is investigating to rule out any connection to the July discharge from the same facility.

The plant operators blame the earlier discharge on the flushing of a sedimentation tank in advance of upgrades. The DEC has requested a detailed report by Sept. 1.